Incorrect detect ruby version #349
Description
When building a unit with multiple ruby versions, the version is incorrectly detect:
configuring Ruby module
checking for Ruby library ... found
checking for Ruby version ... 2.4.9
+ Ruby module: ruby24.unit.so
configuring Ruby module
checking for Ruby library ... found
checking for Ruby version ... 2.4.9
+ Ruby module: ruby25.unit.so
configuring Ruby module
checking for Ruby library ... found
checking for Ruby version ... 2.4.9
+ Ruby module: ruby26.unit.so
ldd ./result/modules/ruby24.unit.so | grep ruby
libruby.so.2.4 => /nix/store/rmr84vhgd5x9rqmygwv2gvmwghsnj1pi-ruby-2.4.9/lib/libruby.so.2.4 (0x0000708222fb5000)
ldd ./result/modules/ruby25.unit.so | grep ruby
libruby.so.2.4 => /nix/store/rmr84vhgd5x9rqmygwv2gvmwghsnj1pi-ruby-2.4.9/lib/libruby.so.2.4 (0x00007544ccdb9000)
ldd ./result/modules/ruby26.unit.so | grep ruby
libruby.so.2.4 => /nix/store/rmr84vhgd5x9rqmygwv2gvmwghsnj1pi-ruby-2.4.9/lib/libruby.so.2.4 (0x0000756de2990000)
Configure module:
./configure ruby --module=ruby24 --ruby=/nix/store/rmr84vhgd5x9rqmygwv2gvmwghsnj1pi-ruby-2.4.9/bin/ruby
./configure ruby --module=ruby25 --ruby=/nix/store/8ihqn72w2v0n02dd99i7x8r9z25xkhsb-ruby-2.5.7/bin/ruby
./configure ruby --module=ruby26 --ruby=/nix/store/b3lhi1wlia02vyd94jk56bm3kvgf1yc0-ruby-2.6.5/bin/ruby